Maternal inflammatory bowel disease and hypospadias in male offspring: a population-based study in Denmark

BACKGROUND The occurrence of inflammatory bowel disease (IBD) and hypospadias has been concurrently increasing, possibly through shared environmental risk factors such as endocrine disrupting compounds. Also, maternal IBD may disturb the normal development of the fetal reproductive tract. However, whether maternal IBD increases the risk of hypospadias in male offspring is unknown. We compared hypospadias risk in sons of mothers with and without IBD. METHODS We used Danish nationwide population-based registries to conduct a longitudinal prevalence study including all live-born boys from 1979 through 2009. We computed HRs, as estimates of prevalence ratios (PRs), with 95% CIs for hypospadias, using Cox proportional hazards regression, while adjusting for measured confounding. RESULTS Among 966 038 live-born boys, 4688 (0.5%) had a mother with a history of IBD diagnosis before the relevant childbirth. Among the boys with maternal IBD, 36 (0.8%) were diagnosed with hypospadias any time after birth, whereas 6112 (0.6%) sons of mothers without IBD diagnosis had hypospadias (adjusted PR: 1.20, (95% CI 0.86 to 1.67). Adjusted PRs for maternal Crohn's disease and ulcerative colitis were 1.38 (95% CI 0.83 to 2.29) and 1.10 (95% CI 0.71 to 1.68), respectively. Analyses defining hypospadias diagnosis recorded <6 months postpartum showed similar results. CONCLUSIONS We found no convincing evidence of an association between maternal IBD and hypospadias.